Effect Of Estradiol Valerate On Expression Of Estrogen Receptor-alpha And Beta In The Uterus And Vagina Of Rats After Ovariectomy

Background and objectiveIt is well-known that hormone replacement herapy(HRT) has become the principal therapic method in women with perimenopausal syndrome. However, long-term use of unopposed estrogens would induce endometrial hyperplasia and increase risk of adenocarcinoma endometrium. In addition, Decreased level of estrogen could lead to telatrophy and hypotonia of female genitourinary tract, and initiate stress urinary incontinence(SUI), but the therapeutic outcome with estrogen is not effective enough, so some researchers hypothesized that SUI might correlate with estrogen receptor. Changes of distribution and content of estrogen receptor alpha(ERα) and estrogen receptor beta(ERβ) could affect drug action of the estrogen. The research results were different about biological effect and interaction of the two subtypes.In present study, we evaluated distribution and coexpression of ERα, ERβin uretus and vagina in adult male SD rats subjected to ovariedctomy and intervention of Estradiol Valerate after ovariedctomy, investigated relationship between changes of ER subtypes, ERα/ERβand endometrial hyperplasia and vaginal atrophy, provide theoretical basis for researching regulation of exogenous estrogen to ER subtypes of uretus and vagina, and appropriate supplying estrogen of postmenopause.Main Methods and results1. A total number of 80 female SD rats aged 4 months weighing about 340g each were randomly assigned into 4 groups: control group (n=20), sham-operated group (n=20), ovariectomied group (n=20) and drug group (n=20). The drug group was treated estradiol valerate everyday by intragastric administration after 4 weeks of Ovariectomy. The other three groups were medicated aequales normal saline by intragastric administration. 8 weeks later, all the rats were killed and the tissues of uterus and vagina and blood sample was collected. Morphological and histopathological changes of uretus and vagina were observed. Levels of estradiol and follicle stimulating hormone(FSH) in plasma were measured. The results showed that there were no estruation changes of vaginal epithelium detected in consecutive 5 days after ovariectomy. Uretus and vagina tissues became athophy, but they return to nomal after drug-taking. HE staining illustrated that endomembrance became atrophy and grand become rarefaction in ovariectomied group, and became thicker after drug-taking. Estradiol Level in plasma decreaed and plasma FSH content elevated significantly. Plasm Estradiol level rised and FSH concentration declined after taking estradiol valerate.2. Immunohistochemistry method and Double-labelling technique of immunofluorescence(DLTI) +Laser scanning confocal microscopy(LSCM) was used to detect the expression and coexpression of ER-αand ER-βin superficial and deep compartments of the Uterus and vagina. The levels of mRNA gene expression of the two subtypes of estrogen receptors were measured by semi-quantitative RT-PCR. (1)The findings demonstrated that estrogen receptor alpha and beta were expressed in luminal epithelial cells, glandular epithelial cells, stromal fibroblast, vascular endothelial cells and the cell nucleus and cytoplasm of smooth muscle cells, especially in luminal epithelial cells and glandular epithelial cells. The Expression of ER alpha is significantly higher than that of ER beta. In terms of the expression of ER alpha, which in the ovariectomied group was lower than that of the control group and sham-operated group and the ratios of ER-α/ER-βis risen. However, there are nearly no expression of the ER beta in the ovariectomied group. The Expression of estrogen receptor alpha in the Uterus was significantly upregulated in drug group, whereas estrogen receptor beta was not upregulated significantly.(2)Estrogen receptor alpha and beta were expressed in squamous epithelial cells, stromal fibroblast, vascular endothelial cells, smooth muscle cells, especially in squamous epithelial cells. The Expression of ER alpha is significantly stronger than that of ER beta. Lower expression of ER isoforms, especially ER beta in ovariectomied group was showed.The Expression of estrogen receptor alpha in the vagina was significantly upregulated in drug group, whereas estrogen receptor beta was not significant up regulated.Conclusions1. successfully establishing animal model of Ovariectomy and drug intervention after Ovariectomy.2. ER-αis a major subtype of Estrogen receptor expressed in uterus of rats. It was demonstrated that the expression of ER was shown lower after ovariectomy, especially that of ER-βand the ratios of ER-α/ER-βis risen. It suggested that estradiol valerate could upregulated expression of ER-αbut not contribution to ER-β.3. ER-αis major expression isoforms of Estrogen receptor in vaginal tissue of rats. It was demonstrated down-regulation of ER-αand ER-βexpression in the vaginal tissues after ovariectomy, especially that of ER-βand the ratios of ER-α/ER-βis risen.The findings showed that estradiol valerate could upregulated expression of ER-αbut ER-β.